\begin{table}[h]
 \centering
 \subtable[$key_5=cbd9$]{
     \begin{tabular}{cc}
         0.0640 & \_b\_f \\
         0.0510 & \_b\_9 \\
         0.0500 & \_e\_6 \\
         0.0480 & \_3\_f \\
         0.0440 & \_e\_4 \\
         0.0430 & \_e\_0 \\
         0.0430 & \_a\_e \\
         0.0420 & \_8\_0 \\
         0.0420 & \_e\_2 \\
         0.0410 & \_d\_9 \\
     \end{tabular}
 }
 \subtable[$key_5=f4aa$]{
     \begin{tabular}{cc}
         0.0510 & \_0\_a \\
         0.0430 & \_b\_7 \\
         0.0410 & \_d\_5 \\
         0.0410 & \_7\_5 \\
         0.0410 & \_4\_2 \\
         0.0400 & \_d\_b \\
         0.0400 & \_3\_5 \\
         0.0390 & \_3\_0 \\
         0.0390 & \_a\_0 \\
         0.0380 & \_3\_a \\
     \end{tabular}
 }
\end{table}
